1. Field of the Invention
The present invention relates to a method and apparatus for providing blood flow during surgical procedures and, more particularly, is directed towards an intercostal lumbar perfusion apparatus and method for providing circulation to distal organs and blood flow to the intercostals during aortic surgery.
2. Description of the Prior Art
Paraplegia is a disastrous complication of aortic surgery which results from ischemia of the spinal cord. This may occur either after application of the cross clamp, if no adjunct is used to provide distal circulation, or after exclusion of the pathologic segment of the aorta with a proximal and distal aortic clamp, when adjuncts like shunt or partial bypass of some sort are employed for maintenance of distal circulation. Use of available techniques to prevent paraplegia are effective only if the major spinal artery is coming off an intercostal in the perfused distal or proximal aorta and the state of the collateral circulation is favorable. Attempts to increase the distal perfusion pressure with partial bypass are not expected to prevent ischemia to the spinal cord in the absence of favorable collateral circulation and distal location of the spinal branch of the posterior intercostals.
Intraoperative monitoring of the spinal cord functions with the use of somatosensory evoked potentials only monitor the functional integrity of the sensory tracts in the posterior spinal cord. Since the collateral circulation between the posterior and anterior spinal arteries varies, ischemic injury to the anterior spinal cord without any damage to the posterior sensory tracts is a possibility. Accordingly, persistent normal intraoperative somatosensory evoked potential, in a given case, does not guarantee absence of postoperative paraplegia. Secondly, in the absence of a secure means for immediate intraoperative reperfusion of the ischemic intercostals, knowledge of changes in somatosensory evoked potentials does not help the patient and may, in fact, force the surgeon to perform a speedy, but inaccurate operation with its associated complications.
Since accurate localization of the spinal branches of the posterior intercostals and details of the collateral circulation cannot be determined preoperatively, a need has arisen for a method and apparatus for preventing paraplegia caused by ischemia to the spinal cord during aortic surgery.